summaryrefslogtreecommitdiff
path: root/src/=unexelf1.c
blob: a832755167e8259ecb498868719704dec7ee87ef (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
/* Copyright (C) 1985, 1986, 1987, 1988, 1990, 1992
   Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.

In other words, you are welcome to use, share and improve this program.
You are forbidden to forbid anyone else to use, share and improve
what you give them.   Help stamp out software-hoarding!  */


/*
 * unexec.c - Convert a running program into an a.out file.
 *
 * Author:	Spencer W. Thomas
 * 		Computer Science Dept.
 * 		University of Utah
 * Date:	Tue Mar  2 1982
 * Modified heavily since then.
 *
 * Synopsis:
 *	unexec (new_name, a_name, data_start, bss_start, entry_address)
 *	char *new_name, *a_name;
 *	unsigned data_start, bss_start, entry_address;
 *
 * Takes a snapshot of the program and makes an a.out format file in the
 * file named by the string argument new_name.
 * If a_name is non-NULL, the symbol table will be taken from the given file.
 * On some machines, an existing a_name file is required.
 *
 * The boundaries within the a.out file may be adjusted with the data_start
 * and bss_start arguments.  Either or both may be given as 0 for defaults.
 *
 * Data_start gives the boundary between the text segment and the data
 * segment of the program.  The text segment can contain shared, read-only
 * program code and literal data, while the data segment is always unshared
 * and unprotected.  Data_start gives the lowest unprotected address.
 * The value you specify may be rounded down to a suitable boundary
 * as required by the machine you are using.
 *
 * Specifying zero for data_start means the boundary between text and data
 * should not be the same as when the program was loaded.
 * If NO_REMAP is defined, the argument data_start is ignored and the
 * segment boundaries are never changed.
 *
 * Bss_start indicates how much of the data segment is to be saved in the
 * a.out file and restored when the program is executed.  It gives the lowest
 * unsaved address, and is rounded up to a page boundary.  The default when 0
 * is given assumes that the entire data segment is to be stored, including
 * the previous data and bss as well as any additional storage allocated with
 * break (2).
 *
 * The new file is set up to start at entry_address.
 *
 * If you make improvements I'd like to get them too.
 * harpo!utah-cs!thomas, thomas@Utah-20
 *
 */

/* Even more heavily modified by james@bigtex.cactus.org of Dell Computer Co.
 * ELF support added.
 *
 * Basic theory: the data space of the running process needs to be
 * dumped to the output file.  Normally we would just enlarge the size
 * of .data, scooting everything down.  But we can't do that in ELF,
 * because there is often something between the .data space and the
 * .bss space.
 *
 * In the temacs dump below, notice that the Global Offset Table
 * (.got) and the Dynamic link data (.dynamic) come between .data1 and
 * .bss.  It does not work to overlap .data with these fields.
 *
 * The solution is to create a new .data segment.  This segment is
 * filled with data from the current process.  Since the contents of
 * various sections refer to sections by index, the new .data segment
 * is made the last in the table to avoid changing any existing index.

 * This is an example of how the section headers are changed.  "Addr"
 * is a process virtual address.  "Offset" is a file offset.

raid:/nfs/raid/src/dist-18.56/src> dump -h temacs

temacs:

           **** SECTION HEADER TABLE ****
[No]    Type    Flags   Addr         Offset       Size          Name
        Link    Info    Adralgn      Entsize

[1]     1       2       0x80480d4    0xd4         0x13          .interp
        0       0       0x1          0

[2]     5       2       0x80480e8    0xe8         0x388         .hash
        3       0       0x4          0x4

[3]     11      2       0x8048470    0x470        0x7f0         .dynsym
        4       1       0x4          0x10

[4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
        0       0       0x1          0

[5]     9       2       0x8049010    0x1010       0x338         .rel.plt
        3       7       0x4          0x8

[6]     1       6       0x8049348    0x1348       0x3           .init
        0       0       0x4          0

[7]     1       6       0x804934c    0x134c       0x680         .plt
        0       0       0x4          0x4

[8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
        0       0       0x4          0

[9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
        0       0       0x4          0

[10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
        0       0       0x4          0

[11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
        0       0       0x4          0

[12]    1       3       0x8088330    0x3f330      0x20afc       .data
        0       0       0x4          0

[13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
        0       0       0x4          0

[14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
        0       0       0x4          0x4

[15]    6       3       0x80a9874    0x60874      0x80          .dynamic
        4       0       0x4          0x8

[16]    8       3       0x80a98f4    0x608f4      0x449c        .bss
        0       0       0x4          0

[17]    2       0       0            0x608f4      0x9b90        .symtab
        18      371     0x4          0x10

[18]    3       0       0            0x6a484      0x8526        .strtab
        0       0       0x1          0

[19]    3       0       0            0x729aa      0x93          .shstrtab
        0       0       0x1          0

[20]    1       0       0            0x72a3d      0x68b7        .comment
        0       0       0x1          0

raid:/nfs/raid/src/dist-18.56/src> dump -h xemacs

xemacs:

           **** SECTION HEADER TABLE ****
[No]    Type    Flags   Addr         Offset       Size          Name
        Link    Info    Adralgn      Entsize

[1]     1       2       0x80480d4    0xd4         0x13          .interp
        0       0       0x1          0

[2]     5       2       0x80480e8    0xe8         0x388         .hash
        3       0       0x4          0x4

[3]     11      2       0x8048470    0x470        0x7f0         .dynsym
        4       1       0x4          0x10

[4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
        0       0       0x1          0

[5]     9       2       0x8049010    0x1010       0x338         .rel.plt
        3       7       0x4          0x8

[6]     1       6       0x8049348    0x1348       0x3           .init
        0       0       0x4          0

[7]     1       6       0x804934c    0x134c       0x680         .plt
        0       0       0x4          0x4

[8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
        0       0       0x4          0

[9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
        0       0       0x4          0

[10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
        0       0       0x4          0

[11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
        0       0       0x4          0

[12]    1       3       0x8088330    0x3f330      0x20afc       .data
        0       0       0x4          0

[13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
        0       0       0x4          0

[14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
        0       0       0x4          0x4

[15]    6       3       0x80a9874    0x60874      0x80          .dynamic
        4       0       0x4          0x8

[16]    8       3       0x80c6800    0x7d800      0             .bss
        0       0       0x4          0

[17]    2       0       0            0x7d800      0x9b90        .symtab
        18      371     0x4          0x10

[18]    3       0       0            0x87390      0x8526        .strtab
        0       0       0x1          0

[19]    3       0       0            0x8f8b6      0x93          .shstrtab
        0       0       0x1          0

[20]    1       0       0            0x8f949      0x68b7        .comment
        0       0       0x1          0

[21]    1       3       0x80a98f4    0x608f4      0x1cf0c       .data
        0       0       0x4          0

 * This is an example of how the file header is changed.  "Shoff" is
 * the section header offset within the file.  Since that table is
 * after the new .data section, it is moved.  "Shnum" is the number of
 * sections, which we increment.
 *
 * "Phoff" is the file offset to the program header.  "Phentsize" and
 * "Shentsz" are the program and section header entries sizes respectively.
 * These can be larger than the apparent struct sizes.

raid:/nfs/raid/src/dist-18.56/src> dump -f temacs

temacs:

                    **** ELF HEADER ****
Class        Data       Type         Machine     Version
Entry        Phoff      Shoff        Flags       Ehsize
Phentsize    Phnum      Shentsz      Shnum       Shstrndx

1            1          2            3           1
0x80499cc    0x34       0x792f4      0           0x34
0x20         5          0x28         21          19

raid:/nfs/raid/src/dist-18.56/src> dump -f xemacs

xemacs:

                    **** ELF HEADER ****
Class        Data       Type         Machine     Version
Entry        Phoff      Shoff        Flags       Ehsize
Phentsize    Phnum      Shentsz      Shnum       Shstrndx

1            1          2            3           1
0x80499cc    0x34       0x96200      0           0x34
0x20         5          0x28         22          19

 * These are the program headers.  "Offset" is the file offset to the
 * segment.  "Vaddr" is the memory load address.  "Filesz" is the
 * segment size as it appears in the file, and "Memsz" is the size in
 * memory.  Below, the third segment is the code and the fourth is the
 * data: the difference between Filesz and Memsz is .bss

raid:/nfs/raid/src/dist-18.56/src> dump -o temacs

temacs:
 ***** PROGRAM EXECUTION HEADER *****
Type        Offset      Vaddr       Paddr
Filesz      Memsz       Flags       Align

6           0x34        0x8048034   0
0xa0        0xa0        5           0

3           0xd4        0           0
0x13        0           4           0

1           0x34        0x8048034   0
0x3f2f9     0x3f2f9     5           0x1000

1           0x3f330     0x8088330   0
0x215c4     0x25a60     7           0x1000

2           0x60874     0x80a9874   0
0x80        0           7           0

raid:/nfs/raid/src/dist-18.56/src> dump -o xemacs

xemacs:
 ***** PROGRAM EXECUTION HEADER *****
Type        Offset      Vaddr       Paddr
Filesz      Memsz       Flags       Align

6           0x34        0x8048034   0
0xa0        0xa0        5           0

3           0xd4        0           0
0x13        0           4           0

1           0x34        0x8048034   0
0x3f2f9     0x3f2f9     5           0x1000

1           0x3f330     0x8088330   0
0x3e4d0     0x3e4d0     7           0x1000

2           0x60874     0x80a9874   0
0x80        0           7           0


 */

/* Modified by wtien@urbana.mcd.mot.com of Motorola Inc.
 *
 * The above mechanism does not work if the unexeced ELF file is being
 * re-layout by other applications (such as `strip'). All the applications
 * that re-layout the internal of ELF will layout all sections in ascending
 * order of their file offsets. After the re-layout, the data2 section will
 * still be the LAST section in the section header vector, but its file offset
 * is now being pushed far away down, and causes part of it not to be mapped
 * in (ie. not covered by the load segment entry in PHDR vector), therefore
 * causes the new binary to fail.
 *
 * The solution is to modify the unexec algorithm to insert the new data2
 * section header right before the new bss section header, so their file
 * offsets will be in the ascending order. Since some of the section's (all
 * sections AFTER the bss section) indexes are now changed, we also need to
 * modify some fields to make them point to the right sections. This is done
 * by macro PATCH_INDEX. All the fields that need to be patched are:
 *
 * 1. ELF header e_shstrndx field.
 * 2. section header sh_link and sh_info field.
 * 3. symbol table entry st_shndx field.
 *
 * The above example now should look like:

           **** SECTION HEADER TABLE ****
[No]    Type    Flags   Addr         Offset       Size          Name
        Link    Info    Adralgn      Entsize

[1]     1       2       0x80480d4    0xd4         0x13          .interp
        0       0       0x1          0

[2]     5       2       0x80480e8    0xe8         0x388         .hash
        3       0       0x4          0x4

[3]     11      2       0x8048470    0x470        0x7f0         .dynsym
        4       1       0x4          0x10

[4]     3       2       0x8048c60    0xc60        0x3ad         .dynstr
        0       0       0x1          0

[5]     9       2       0x8049010    0x1010       0x338         .rel.plt
        3       7       0x4          0x8

[6]     1       6       0x8049348    0x1348       0x3           .init
        0       0       0x4          0

[7]     1       6       0x804934c    0x134c       0x680         .plt
        0       0       0x4          0x4

[8]     1       6       0x80499cc    0x19cc       0x3c56f       .text
        0       0       0x4          0

[9]     1       6       0x8085f3c    0x3df3c      0x3           .fini
        0       0       0x4          0

[10]    1       2       0x8085f40    0x3df40      0x69c         .rodata
        0       0       0x4          0

[11]    1       2       0x80865dc    0x3e5dc      0xd51         .rodata1
        0       0       0x4          0

[12]    1       3       0x8088330    0x3f330      0x20afc       .data
        0       0       0x4          0

[13]    1       3       0x80a8e2c    0x5fe2c      0x89d         .data1
        0       0       0x4          0

[14]    1       3       0x80a96cc    0x606cc      0x1a8         .got
        0       0       0x4          0x4

[15]    6       3       0x80a9874    0x60874      0x80          .dynamic
        4       0       0x4          0x8

[16]    1       3       0x80a98f4    0x608f4      0x1cf0c       .data
        0       0       0x4          0

[17]    8       3       0x80c6800    0x7d800      0             .bss
        0       0       0x4          0

[18]    2       0       0            0x7d800      0x9b90        .symtab
        19      371     0x4          0x10

[19]    3       0       0            0x87390      0x8526        .strtab
        0       0       0x1          0

[20]    3       0       0            0x8f8b6      0x93          .shstrtab
        0       0       0x1          0

[21]    1       0       0            0x8f949      0x68b7        .comment
        0       0       0x1          0

 */

#include <sys/types.h>
#include <stdio.h>
#include <sys/stat.h>
#include <memory.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <elf.h>
#include <sys/mman.h>

#ifdef __alpha__
# include <sym.h>	/* get COFF debugging symbol table declaration */
#endif

#if __GNU_LIBRARY__ - 0 >= 6
# include <link.h>	/* get ElfW etc */
#endif

#ifndef ElfW
# ifdef __STDC__
#  define ElfW(type)	Elf32_##type
# else
#  define ElfW(type)	Elf32_/**/type
# endif
#endif

#ifndef emacs
#define fatal(a, b, c) fprintf (stderr, a, b, c), exit (1)
#else
#include <config.h>
extern void fatal (char *, ...);
#endif

#ifndef ELF_BSS_SECTION_NAME
#define ELF_BSS_SECTION_NAME ".bss"
#endif

/* Get the address of a particular section or program header entry,
 * accounting for the size of the entries.
 */
/* 
   On PPC Reference Platform running Solaris 2.5.1
   the plt section is also of type NOBI like the bss section.
   (not really stored) and therefore sections after the bss
   section start at the plt offset. The plt section is always
   the one just before the bss section.
   Thus, we modify the test from
      if (NEW_SECTION_H (nn).sh_offset >= new_data2_offset)
   to
      if (NEW_SECTION_H (nn).sh_offset >= 
               OLD_SECTION_H (old_bss_index-1).sh_offset)
   This is just a hack. We should put the new data section
   before the .plt section.
   And we should not have this routine at all but use
   the libelf library to read the old file and create the new
   file.
   The changed code is minimal and depends on prep set in m/prep.h
   Erik Deumens
   Quantum Theory Project
   University of Florida
   deumens@qtp.ufl.edu
   Apr 23, 1996
   */

#define OLD_SECTION_H(n) \
     (*(ElfW(Shdr) *) ((byte *) old_section_h + old_file_h->e_shentsize * (n)))
#define NEW_SECTION_H(n) \
     (*(ElfW(Shdr) *) ((byte *) new_section_h + new_file_h->e_shentsize * (n)))
#define OLD_PROGRAM_H(n) \
     (*(ElfW(Phdr) *) ((byte *) old_program_h + old_file_h->e_phentsize * (n)))
#define NEW_PROGRAM_H(n) \
     (*(ElfW(Phdr) *) ((byte *) new_program_h + new_file_h->e_phentsize * (n)))

#define PATCH_INDEX(n) \
  do { \
	 if ((int) (n) >= old_bss_index) \
	   (n)++; } while (0)
typedef unsigned char byte;

/* Round X up to a multiple of Y.  */

int
round_up (x, y)
     int x, y;
{
  int rem = x % y;
  if (rem == 0)
    return x;
  return x - rem + y;
}

/* ****************************************************************
 * unexec
 *
 * driving logic.
 *
 * In ELF, this works by replacing the old .bss section with a new
 * .data section, and inserting an empty .bss immediately afterwards.
 *
 */
void
unexec (new_name, old_name, data_start, bss_start, entry_address)
     char *new_name, *old_name;
     unsigned data_start, bss_start, entry_address;
{
  int new_file, old_file, new_file_size;

  /* Pointers to the base of the image of the two files. */
  caddr_t old_base, new_base;

  /* Pointers to the file, program and section headers for the old and new
   * files.
   */
  ElfW(Ehdr) *old_file_h, *new_file_h;
  ElfW(Phdr) *old_program_h, *new_program_h;
  ElfW(Shdr) *old_section_h, *new_section_h;

  /* Point to the section name table in the old file */
  char *old_section_names;

  ElfW(Addr) old_bss_addr, new_bss_addr;
  ElfW(Word) old_bss_size, new_data2_size;
  ElfW(Off)  new_data2_offset;
  ElfW(Addr) new_data2_addr;

  int n, nn, old_bss_index, old_data_index, new_data2_index;
  struct stat stat_buf;

  /* Open the old file & map it into the address space. */

  old_file = open (old_name, O_RDONLY);

  if (old_file < 0)
    fatal ("Can't open %s for reading: errno %d\n", old_name, errno);

  if (fstat (old_file, &stat_buf) == -1)
    fatal ("Can't fstat (%s): errno %d\n", old_name, errno);

  old_base = mmap (0, stat_buf.st_size, PROT_READ, MAP_SHARED, old_file, 0);

  if (old_base == (caddr_t) -1)
    fatal ("Can't mmap (%s): errno %d\n", old_name, errno);

#ifdef DEBUG
  fprintf (stderr, "mmap (%s, %x) -> %x\n", old_name, stat_buf.st_size,
	   old_base);
#endif

  /* Get pointers to headers & section names */

  old_file_h = (ElfW(Ehdr) *) old_base;
  old_program_h = (ElfW(Phdr) *) ((byte *) old_base + old_file_h->e_phoff);
  old_section_h = (ElfW(Shdr) *) ((byte *) old_base + old_file_h->e_shoff);
  old_section_names = (char *) old_base
    + OLD_SECTION_H (old_file_h->e_shstrndx).sh_offset;

  /* Find the old .bss section.  Figure out parameters of the new
   * data2 and bss sections.
   */

  for (old_bss_index = 1; old_bss_index < (int) old_file_h->e_shnum;
       old_bss_index++)
    {
#ifdef DEBUG
      fprintf (stderr, "Looking for .bss - found %s\n",
	       old_section_names + OLD_SECTION_H (old_bss_index).sh_name);
#endif
      if (!strcmp (old_section_names + OLD_SECTION_H (old_bss_index).sh_name,
		   ELF_BSS_SECTION_NAME))
	break;
    }
  if (old_bss_index == old_file_h->e_shnum)
    fatal ("Can't find .bss in %s.\n", old_name, 0);

  old_bss_addr = OLD_SECTION_H (old_bss_index).sh_addr;
  old_bss_size = OLD_SECTION_H (old_bss_index).sh_size;
#if defined(emacs) || !defined(DEBUG)
  new_bss_addr = (ElfW(Addr)) sbrk (0);
#else
  new_bss_addr = old_bss_addr + old_bss_size + 0x1234;
#endif
  new_data2_addr = old_bss_addr;
  new_data2_size = new_bss_addr - old_bss_addr;
  new_data2_offset = OLD_SECTION_H (old_bss_index).sh_offset;

#ifdef DEBUG
  fprintf (stderr, "old_bss_index %d\n", old_bss_index);
  fprintf (stderr, "old_bss_addr %x\n", old_bss_addr);
  fprintf (stderr, "old_bss_size %x\n", old_bss_size);
  fprintf (stderr, "new_bss_addr %x\n", new_bss_addr);
  fprintf (stderr, "new_data2_addr %x\n", new_data2_addr);
  fprintf (stderr, "new_data2_size %x\n", new_data2_size);
  fprintf (stderr, "new_data2_offset %x\n", new_data2_offset);
#endif

  if ((unsigned) new_bss_addr < (unsigned) old_bss_addr + old_bss_size)
    fatal (".bss shrank when undumping???\n", 0, 0);

  /* Set the output file to the right size and mmap it.  Set
   * pointers to various interesting objects.  stat_buf still has
   * old_file data.
   */

  new_file = open (new_name, O_RDWR | O_CREAT, 0666);
  if (new_file < 0)
    fatal ("Can't creat (%s): errno %d\n", new_name, errno);

  new_file_size = stat_buf.st_size + old_file_h->e_shentsize + new_data2_size;

  if (ftruncate (new_file, new_file_size))
    fatal ("Can't ftruncate (%s): errno %d\n", new_name, errno);

#ifdef UNEXEC_USE_MAP_PRIVATE
  new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
		   new_file, 0);
#else
  new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_SHARED,
		   new_file, 0);
#endif

  if (new_base == (caddr_t) -1)
    fatal ("Can't mmap (%s): errno %d\n", new_name, errno);

  new_file_h = (ElfW(Ehdr) *) new_base;
  new_program_h = (ElfW(Phdr) *) ((byte *) new_base + old_file_h->e_phoff);
  new_section_h = (ElfW(Shdr) *)
    ((byte *) new_base + old_file_h->e_shoff + new_data2_size);

  /* Make our new file, program and section headers as copies of the
   * originals.
   */

  memcpy (new_file_h, old_file_h, old_file_h->e_ehsize);
  memcpy (new_program_h, old_program_h,
	  old_file_h->e_phnum * old_file_h->e_phentsize);

  /* Modify the e_shstrndx if necessary. */
  PATCH_INDEX (new_file_h->e_shstrndx);

  /* Fix up file header.  We'll add one section.  Section header is
   * further away now.
   */

  new_file_h->e_shoff += new_data2_size;
  new_file_h->e_shnum += 1;

#ifdef DEBUG
  fprintf (stderr, "Old section offset %x\n", old_file_h->e_shoff);
  fprintf (stderr, "Old section count %d\n", old_file_h->e_shnum);
  fprintf (stderr, "New section offset %x\n", new_file_h->e_shoff);
  fprintf (stderr, "New section count %d\n", new_file_h->e_shnum);
#endif

  /* Fix up a new program header.  Extend the writable data segment so
   * that the bss area is covered too. Find that segment by looking
   * for a segment that ends just before the .bss area.  Make sure
   * that no segments are above the new .data2.  Put a loop at the end
   * to adjust the offset and address of any segment that is above
   * data2, just in case we decide to allow this later.
   */

  for (n = new_file_h->e_phnum - 1; n >= 0; n--)
    {
      /* Compute maximum of all requirements for alignment of section.  */
      int alignment = (NEW_PROGRAM_H (n)).p_align;
      if ((OLD_SECTION_H (old_bss_index)).sh_addralign > alignment)
	alignment = OLD_SECTION_H (old_bss_index).sh_addralign;

      if (NEW_PROGRAM_H (n).p_vaddr + NEW_PROGRAM_H (n).p_filesz > old_bss_addr)
	fatal ("Program segment above .bss in %s\n", old_name, 0);

      if (NEW_PROGRAM_H (n).p_type == PT_LOAD
	  && (round_up ((NEW_PROGRAM_H (n)).p_vaddr
			+ (NEW_PROGRAM_H (n)).p_filesz,
			alignment)
	      == round_up (old_bss_addr, alignment)))
	break;
    }
  if (n < 0)
    fatal ("Couldn't find segment next to .bss in %s\n", old_name, 0);

  NEW_PROGRAM_H (n).p_filesz += new_data2_size;
  NEW_PROGRAM_H (n).p_memsz = NEW_PROGRAM_H (n).p_filesz;

#if 0 /* Maybe allow section after data2 - does this ever happen? */
  for (n = new_file_h->e_phnum - 1; n >= 0; n--)
    {
      if (NEW_PROGRAM_H (n).p_vaddr
	  && NEW_PROGRAM_H (n).p_vaddr >= new_data2_addr)
	NEW_PROGRAM_H (n).p_vaddr += new_data2_size - old_bss_size;

      if (NEW_PROGRAM_H (n).p_offset >= new_data2_offset)
	NEW_PROGRAM_H (n).p_offset += new_data2_size;
    }
#endif

  /* Fix up section headers based on new .data2 section.  Any section
   * whose offset or virtual address is after the new .data2 section
   * gets its value adjusted.  .bss size becomes zero and new address
   * is set.  data2 section header gets added by copying the existing
   * .data header and modifying the offset, address and size.
   */
  for (old_data_index = 1; old_data_index < (int) old_file_h->e_shnum;
       old_data_index++)
    if (!strcmp (old_section_names + OLD_SECTION_H (old_data_index).sh_name,
		 ".data"))
      break;
  if (old_data_index == old_file_h->e_shnum)
    fatal ("Can't find .data in %s.\n", old_name, 0);

  /* Walk through all section headers, insert the new data2 section right
     before the new bss section. */
  for (n = 1, nn = 1; n < (int) old_file_h->e_shnum; n++, nn++)
    {
      caddr_t src;
      /* If it is bss section, insert the new data2 section before it. */
      if (n == old_bss_index)
	{
	  /* Steal the data section header for this data2 section. */
	  memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (old_data_index),
		  new_file_h->e_shentsize);

	  NEW_SECTION_H (nn).sh_addr = new_data2_addr;
	  NEW_SECTION_H (nn).sh_offset = new_data2_offset;
	  NEW_SECTION_H (nn).sh_size = new_data2_size;
	  /* Use the bss section's alignment. This will assure that the
	     new data2 section always be placed in the same spot as the old
	     bss section by any other application. */
	  NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (n).sh_addralign;

	  /* Now copy over what we have in the memory now. */
	  memcpy (NEW_SECTION_H (nn).sh_offset + new_base,
		  (caddr_t) OLD_SECTION_H (n).sh_addr,
		  new_data2_size);
	  nn++;
	}

      memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (n),
	      old_file_h->e_shentsize);

      /* The new bss section's size is zero, and its file offset and virtual
	 address should be off by NEW_DATA2_SIZE. */
      if (n == old_bss_index)
	{
	  /* NN should be `old_bss_index + 1' at this point. */
	  NEW_SECTION_H (nn).sh_offset += new_data2_size;
	  NEW_SECTION_H (nn).sh_addr += new_data2_size;
	  /* Let the new bss section address alignment be the same as the
	     section address alignment followed the old bss section, so
	     this section will be placed in exactly the same place. */
	  NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (nn).sh_addralign;
	  NEW_SECTION_H (nn).sh_size = 0;
	}
      else
	{
	  /* Any section that was original placed AFTER the bss
	     section should now be off by NEW_DATA2_SIZE. */
#ifdef SOLARIS_POWERPC
	  /* On PPC Reference Platform running Solaris 2.5.1
	     the plt section is also of type NOBI like the bss section.
	     (not really stored) and therefore sections after the bss
	     section start at the plt offset. The plt section is always
	     the one just before the bss section.
	     It would be better to put the new data section before
	     the .plt section, or use libelf instead.
	     Erik Deumens, deumens@qtp.ufl.edu.  */
	  if (NEW_SECTION_H (nn).sh_offset
	      >= OLD_SECTION_H (old_bss_index-1).sh_offset)
	    NEW_SECTION_H (nn).sh_offset += new_data2_size;
#else
	  if (round_up (NEW_SECTION_H (nn).sh_offset,
			OLD_SECTION_H (old_bss_index).sh_addralign)
	      >= new_data2_offset)
	    NEW_SECTION_H (nn).sh_offset += new_data2_size;
#endif
	  /* Any section that was originally placed after the section
	     header table should now be off by the size of one section
	     header table entry.  */
	  if (NEW_SECTION_H (nn).sh_offset > new_file_h->e_shoff)
	    NEW_SECTION_H (nn).sh_offset += new_file_h->e_shentsize;
	}

      /* If any section hdr refers to the section after the new .data
	 section, make it refer to next one because we have inserted
	 a new section in between.  */

      PATCH_INDEX (NEW_SECTION_H (nn).sh_link);
      /* For symbol tables, info is a symbol table index,
	 so don't change it.  */
      if (NEW_SECTION_H (nn).sh_type != SHT_SYMTAB
	  && NEW_SECTION_H (nn).sh_type != SHT_DYNSYM)
	PATCH_INDEX (NEW_SECTION_H (nn).sh_info);

      /* Now, start to copy the content of sections.  */
      if (NEW_SECTION_H (nn).sh_type == SHT_NULL
	  || NEW_SECTION_H (nn).sh_type == SHT_NOBITS)
	continue;

      /* Write out the sections. .data and .data1 (and data2, called
	 ".data" in the strings table) get copied from the current process
	 instead of the old file.  */
      if (!strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".data")
	  || !strcmp ((old_section_names + NEW_SECTION_H (n).sh_name),
		      ".data1"))
	src = (caddr_t) OLD_SECTION_H (n).sh_addr;
      else
	src = old_base + OLD_SECTION_H (n).sh_offset;

      memcpy (NEW_SECTION_H (nn).sh_offset + new_base, src,
	      NEW_SECTION_H (nn).sh_size);

#ifdef __alpha__
      /* Update Alpha COFF symbol table: */
      if (strcmp (old_section_names + OLD_SECTION_H (n).sh_name, ".mdebug")
	  == 0)
	{
	  pHDRR symhdr = (pHDRR) (NEW_SECTION_H (nn).sh_offset + new_base);

	  symhdr->cbLineOffset += new_data2_size;
	  symhdr->cbDnOffset += new_data2_size;
	  symhdr->cbPdOffset += new_data2_size;
	  symhdr->cbSymOffset += new_data2_size;
	  symhdr->cbOptOffset += new_data2_size;
	  symhdr->cbAuxOffset += new_data2_size;
	  symhdr->cbSsOffset += new_data2_size;
	  symhdr->cbSsExtOffset += new_data2_size;
	  symhdr->cbFdOffset += new_data2_size;
	  symhdr->cbRfdOffset += new_data2_size;
	  symhdr->cbExtOffset += new_data2_size;
	}
#endif /* __alpha__ */

      /* If it is the symbol table, its st_shndx field needs to be patched.  */
      if (NEW_SECTION_H (nn).sh_type == SHT_SYMTAB
	  || NEW_SECTION_H (nn).sh_type == SHT_DYNSYM)
	{
	  ElfW(Shdr) *spt = &NEW_SECTION_H (nn);
	  unsigned int num = spt->sh_size / spt->sh_entsize;
	  ElfW(Sym) * sym = (ElfW(Sym) *) (NEW_SECTION_H (nn).sh_offset +
					   new_base);
	  for (; num--; sym++)
	    {
	      if ((sym->st_shndx == SHN_UNDEF)
		  || (sym->st_shndx == SHN_ABS)
		  || (sym->st_shndx == SHN_COMMON))
		continue;

	      PATCH_INDEX (sym->st_shndx);
	    }
	}
    }

  /* Update the symbol values of _edata and _end.  */
  for (n = new_file_h->e_shnum - 1; n; n--)
    {
      byte *symnames;
      ElfW(Sym) *symp, *symendp;

      if (NEW_SECTION_H (n).sh_type != SHT_DYNSYM
	  && NEW_SECTION_H (n).sh_type != SHT_SYMTAB)
	continue;

      symnames = ((byte *) new_base
		  + NEW_SECTION_H (NEW_SECTION_H (n).sh_link).sh_offset);
      symp = (ElfW(Sym) *) (NEW_SECTION_H (n).sh_offset + new_base);
      symendp = (ElfW(Sym) *) ((byte *)symp + NEW_SECTION_H (n).sh_size);

      for (; symp < symendp; symp ++)
	if (strcmp ((char *) (symnames + symp->st_name), "_end") == 0
	    || strcmp ((char *) (symnames + symp->st_name), "_edata") == 0)
	  memcpy (&symp->st_value, &new_bss_addr, sizeof (new_bss_addr));
    }

  /* This loop seeks out relocation sections for the data section, so
     that it can undo relocations performed by the runtime linker.  */
  for (n = new_file_h->e_shnum - 1; n; n--)
    {
      ElfW(Shdr) section = NEW_SECTION_H (n);
      switch (section.sh_type) {
      default:
	break;
      case SHT_REL:
      case SHT_RELA:
	/* This code handles two different size structs, but there should
	   be no harm in that provided that r_offset is always the first
	   member.  */
	nn = section.sh_info;
	if (!strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".data")
	    || !strcmp ((old_section_names + NEW_SECTION_H (nn).sh_name),
			".data1"))
	  {
	    ElfW(Addr) offset = NEW_SECTION_H (nn).sh_addr -
	      NEW_SECTION_H (nn).sh_offset;
	    caddr_t reloc = old_base + section.sh_offset, end;
	    for (end = reloc + section.sh_size; reloc < end;
		 reloc += section.sh_entsize)
	      {
		ElfW(Addr) addr = ((ElfW(Rel) *) reloc)->r_offset - offset;
#ifdef __alpha__
		/* The Alpha ELF binutils currently have a bug that
		   sometimes results in relocs that contain all
		   zeroes.  Work around this for now...  */
		if (((ElfW(Rel) *) reloc)->r_offset == 0)
		    continue;
#endif
		memcpy (new_base + addr, old_base + addr, sizeof(ElfW(Addr)));
	      }
	  }
	break;
      }
    }

#ifdef UNEXEC_USE_MAP_PRIVATE
  if (lseek (new_file, 0, SEEK_SET) == -1)
    fatal ("Can't rewind (%s): errno %d\n", new_name, errno);

  if (write (new_file, new_base, new_file_size) != new_file_size)
    fatal ("Can't write (%s): errno %d\n", new_name, errno);
#endif

  /* Close the files and make the new file executable.  */

  if (close (old_file))
    fatal ("Can't close (%s): errno %d\n", old_name, errno);

  if (close (new_file))
    fatal ("Can't close (%s): errno %d\n", new_name, errno);

  if (stat (new_name, &stat_buf) == -1)
    fatal ("Can't stat (%s): errno %d\n", new_name, errno);

  n = umask (777);
  umask (n);
  stat_buf.st_mode |= 0111 & ~n;
  if (chmod (new_name, stat_buf.st_mode) == -1)
    fatal ("Can't chmod (%s): errno %d\n", new_name, errno);
}